Having trouble achieving 1Gbit UDP throughput

Question

For UDP packets with a payload less then 1470, is it possible to achieve 1Gbit throughput? Due to the small packet size, there should be some bottlenecks in achieving such t

Answer 1

I've previously done some experimenting with throughput on gigabit links on relatively standard pc hardware, albeit doing just transmits (via tcpreplay), rather than udp.

The biggest bottleneck that I found was in just getting packets to the NIC itself. This can be significantly improved by using a high speed bus to interface to your NIC (eg. a 4x pci-express NIC). But even with this there was a very definate packet/second limit. Obviously increasing the packet size would allow you to utilize more of your bandwidth while reducing processor load.

Along the same lines as the comment by Steve Moyer, there is a theoretical limit for the utilization of any network. In my experiments (which were being done on a completely quiet network) I was seeing a maximum of approximately (and only off the top of my memory) 900Mb/s. This was with cpu loads of 30 to 40%.

It's more likely that the limitation is going to be imposed by your system hardware (ie. PC) than your network infrastructure - any network switch worth its salt should be capable of sustaining full speed network access with small packets - certainly at much higher rates than most PCs can cope with.